NMR spectroscopy will be used to study biological supramolecular structures. The systems chosen for these investigations are the filamentous bacteriophage fd and the fd gene 5 protein-DNA complex. There are two goals to the proposed research: 1) development and application of NMR methods for the study of highly ordered high molecular weight structures, 2) a detailed description of DNA-protein interactions and the effect of extended quaternary structure on protein conformation and dynamics. Proton-enhanced NMR will be used to overcome the potentially devastating effects of static dipolar broadening and long relaxation times of high molecular weight polymers. In addition, protein subunits will be studied in solution by high resolution 13C and 2H NMR. Both forms of spectroscopy are designed to isolate one of three readily interpretable spin interactions: dipolar couplings, chemical shift anisotropy, and quadrupolar couplings. The bacteriophage fd infects E. coli, therefore isotopically labelled amino acids can be incorporated into the viral proteins. The fd virion is a particularly favorable structure because it can be oriented well enough for X-ray diffraction studies and is made up of 2,400 copies of a very small coat protein that are symmetrically arranged. The gene 5 protein binds cooperatively to DNA, forming a high molecular weight DNA-protein complex. Both of these DNA binding proteins can be studied in the form of isolated subunits and as part of a supramolecular structure.